--- a/xpcom/typelib/xpt/xpt_struct.cpp
+++ b/xpcom/typelib/xpt/xpt_struct.cpp
@@ -181,17 +181,17 @@ XPT_DoHeader(XPTArena *arena, NotNull<XP
     return true;
 }
 
 /* InterfaceDirectoryEntry records go in the header */
 bool
 DoInterfaceDirectoryEntry(XPTArena *arena, NotNull<XPTCursor*> cursor,
                           XPTInterfaceDirectoryEntry *ide)
 {
-    char* dummy_name_space;
+    const char* dummy_name_space;
 
     /* write the IID in our cursor space */
     if (!XPT_DoIID(cursor, &(ide->iid)) ||
 
         /* write the name string in the data pool, and the offset in our
            cursor space */
         !XPT_DoCString(arena, cursor, &(ide->name)) ||
 

--- a/xpcom/typelib/xpt/xpt_struct.h
+++ b/xpcom/typelib/xpt/xpt_struct.h
@@ -67,21 +67,21 @@ struct XPTHeader {
 /*
  * A contiguous array of fixed-size InterfaceDirectoryEntry records begins at
  * the byte offset identified by the interface_directory field in the file
  * header.  The array is used to quickly locate an interface description
  * using its IID.  No interface should appear more than once in the array.
  */
 struct XPTInterfaceDirectoryEntry {
   nsID iid;
-  char* name;
+  const char* name;
 
   // This field exists in the on-disk format. But it isn't used so we don't
   // allocate space for it in memory.
-  //char* name_space;
+  //const char* name_space;
 
   XPTInterfaceDescriptor* interface_descriptor;
 };
 
 /*
  * An InterfaceDescriptor describes a single XPCOM interface, including all of
  * its methods.
  */
@@ -242,17 +242,17 @@ struct XPTTypeDescriptor {
 union XPTConstValue {
   int16_t i16;
   uint16_t ui16;
   int32_t i32;
   uint32_t ui32;
 }; /* varies according to type */
 
 struct XPTConstDescriptor {
-  char* name;
+  const char* name;
   XPTTypeDescriptor type;
   union XPTConstValue value;
 };
 
 /*
  * A ParamDescriptor is a variable-size record used to describe either a
  * single argument to a method or a method's result.
  */
@@ -261,16 +261,16 @@ struct XPTParamDescriptor {
   XPTTypeDescriptor type;
 };
 
 /*
  * A MethodDescriptor is a variable-size record used to describe a single
  * interface method.
  */
 struct XPTMethodDescriptor {
-  char* name;
+  const char* name;
   XPTParamDescriptor* params;
   //XPTParamDescriptor result; // Present on disk, omitted here.
   uint8_t flags;
   uint8_t num_args;
 };
 
 #endif /* xpt_struct_h */

--- a/xpcom/typelib/xpt/xpt_xdr.cpp
+++ b/xpcom/typelib/xpt/xpt_xdr.cpp
@@ -106,17 +106,17 @@ XPT_SkipStringInline(NotNull<XPTCursor*>
     for (uint16_t i = 0; i < length; i++)
         if (!XPT_Do8(cursor, &byte))
             return false;
 
     return true;
 }
 
 bool
-XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, char **identp,
+XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, const char **identp,
               bool ignore)
 {
     uint32_t offset = 0;
     if (!XPT_Do32(cursor, &offset))
         return false;
 
     if (!offset) {
         *identp = NULL;

--- a/xpcom/typelib/xpt/xpt_xdr.h
+++ b/xpcom/typelib/xpt/xpt_xdr.h
@@ -19,17 +19,17 @@ using mozilla::NotNull;
 struct XPTArena;
 struct XPTCursor;
 struct XPTState;
 
 bool
 XPT_SkipStringInline(NotNull<XPTCursor*> cursor);
 
 bool
-XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, char **strp,
+XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, const char **strp,
               bool ignore = false);
 
 bool
 XPT_DoIID(NotNull<XPTCursor*> cursor, nsID *iidp);
 
 bool
 XPT_Do64(NotNull<XPTCursor*> cursor, int64_t *u64p);